Circuit interrupter



Feb. 1, 1949. J. M. CUMMING CIRCUIT INTERRUPTER 2 Sheets-Sheet l FiledSept. 12, 1946 Insu/a f/on /Z-0// l eve/ INVENTOR fan as M Cumm/hy Bi/ WATTORN WITNESS-If; 5. 4 77% 2 3?. 626,02:

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CIRCUIT INTERRUPTER Filed Sept. 12, 1946 2 Sheets-Sheet 2 Patented Feb.1, T949 UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTER James M.Cumming, Turtle Creek, Pa., assignor to Westinghouse ElectricCorporation, East Pittsburgh, Pa., a corporation of PennsylvaniaApplication September 12, 1946, Serial No. 696,571

9 Claims. 1

This invention relates to circuit interrupters in general and moreparticularly to improved arcextinguishing structures therefor.

A general object of my invention is to provide an improved circuitinterrupter in which the arcs established therein will more quickly andeffectively be interrupted than heretofore.

A further object of my invention is to provide a circuit interrupterusing only a small quantity of fluid, and preferably of the singlebushing type.

A more specific object of my invention is to provide an improved circuitinterrupter in which the structural positioning of the several parts isimproved over the constructions employed heretofore. More specifically,my invention is concerned with operating constructions which willpositively establish the arcs and will effectively interrupt themquickly over the entire current range.

Another object is to provide an improved arcextinguishing unit in whicha pair of interrupting chambers are disposed at opposite ends of theunit and in which an improved pressure-generating chamber is providedintermediate the ends of the unit. Preferably, an improved low currentpiston construction is disposed within the pressure-generating chamberto facilitate the inter ruption of low currents where the pressuregenerated at the pressure-generating arc is not sumcient to provide therequisite fluid flow toward the interrupting arcs.

Another object is to provide an improved contacting holding engagementbetween the actuating movable contact and the operating rods within theunit which cause positive movement of the contact structure within thearc-extinguishing unit.

Further objects and advantages will readily become apparent upon areading of the following specification taken in conjunction with thedrawings, in which:

Figure 1 is a side elevational view of a complete circuit interrupterembodying my invention;

Fig. 2 is an enlarged side elevational view, partly in vertical section,of the improved circuit interrupter of Fig. 1;

Fig. 3 is a vertical sectional view through the improvedarc-extinguishing unit of my invention on the line III-III of Fig. 5,the contacts being shown in the partly open circuit position and thecurrent conditions being assumed to be high so that the low currentpiston is held back;

Fig. 4 is a sectional view taken along the line 2 IV-IV of Fig. 3looking in the direction of the arrows;

Fig. 5 is a sectional view taken along the line V V of Fig. 3 looking inthe direction of the arrows.

Fig. 6 is an enlarged fragmentary view of a contact structure in whichthe taper is so large that the two contacts will not hold together, and

Fig. '7 is an enlarged fragmentary view of my improved contact holdingdevice taken on the line VII-VII of Fig. 3 in the direction of thearrows.

Referring to the drawings, and more particularly to Fig. 1 thereof, thereference numeral I designates a base upon which is mounted verticallyextending structural framework comprising a plurality of vertical angleirons 2 braced by diagonally extending angle irons 3 and supporting atthe upper end thereof a horizontally extending support generallydesignated by the reference numeral 4. The support 4 supports rigidly inposition a circuit interrupter of the oilpoor type generally designatedby the reference numeral 5 and including a high voltage condenserbushing 6 extending through a support plate 1 and having anarc-extinguishing unit 8 threadedly secured and clamped to the lower endof the bushing as at 9.

The arc-extinguishing unit 8 is immersed in a suitable arc-extinguishingliquid l0 filling the casing H to the level l2. The casing ll comprisesan internally disposed cylindrical insulating cylinder I 3 and anexternally disposed porcelain cylinder l4, Preferably, the insulatingcylinder I3 is maintained in tension and the porcelain cylinder [4maintained in compression. This is accomplished in the present instanceby employing a plurality of spring washers l5, the outer periphery ofwhich make engagement with a metallic cylindrical member 16 having theupper end thereof bearing against the lower end of the porcelain casingM. The spring washers ii are bolted at their inner side by bolts I! toan annular clamp f8 secured to the lower end of the insulating tube l3.The clamp 18 also supports a stationary guide casting l9 which serves toguide during the opening and closing operations of the interrupter alower movable contact 20.

The lower movable contact 20 is pivotally connected at 2| to aninsulating operating rod 22 pivotally connected at its upper end at 23to a crank 24, the right-hand end of which is rigidly secured to anoperating shaft 25. The operating shaft 25 may be actuated externally ofthe metallic housing 26 by a crank arm 27 (Fig. 2). Consequently, duringthe opening and closing operations the crank arm 2'! is rotativelyoperated to cause through the linkage 22, 24 vertically reciprocatingmotion of the lower movable contact 29.

Certain of the mounting features herein described are set forth andclaimed in United States patent application, filed May 19, 1945, SerialNumber 59%, 634, by Leon R. Ludwig and Benjamin P. Baker, and assignedto the assignee of i this invention.

Referring more particularly to Fig. 3 which shows enlarged a verticalsectional view through the arc-extinguishing unit 8, it will be observedthat in my improved construction I have employed an intermediatelydisposed castingmem ber 28 which has its ends bolted to metallic platemembers 29, 30. Two sets of insulating tie rods. 3! (Fig. 4) secure thetwo stacks of insulatin plate members to the metallic plates 29, 38 andto the top and bottom metallic plates 32, 56 of the unit 23. Preferably,the top metallic plate 32 is an integral part of the contact foot 33which is. clamped to the lower end of the bushing 6. The.arc-extinguishing unit 8 includes an upper interrupting chambergenerally designated by the reference numeral a lower interruptingchamber generally designated by the reference numeral 35 and a centrallyor intermediately positioned pressure-generating chamber, generallydesignated by the reference numeral 35.

Carriage means including two insulating operating rods 31 are utilizedin the construction shown in Fig. 3 andextend interiorly longitudinallyof the unit 8, having their lower ends bridged by a conducting bridgingmember 38, and'th-eir upper ends bridged by a second conducting bridgingmember 39. Preferably, the upper ends of the rods 31- make threadedengagement, as at 58, with the conducting bridge 39. Studs M areinserted into the lower ends of the operating rods 37: and cooperatewith nuts 42 to maintain the operating rods 31 securely clamped to thelower conducting bridge 53.

. "Extending upwardly through an outer insulating sleeve 43 from thecentral portion of the upper conducting bridging member 39 is an uppermovable interrupting contact 44. The movable contact ld. cooperates withan upper relatively stationary contact 35 to establish a first or upperinterrupting are 46 within the interrupting chamber 34.

The upper movable interrupting contact id is threadedly secured toamovable pressure-generating contact A! which cooperates with arelatively' stationary pressure-generating contact 48 to establish apressure-generating are 49 within the pressure-generating chamber 3t.

Extending upwardly from the central portion of the lower conductingbridge member 38 is a movable interrupting contact 58 which cooperateswith a relatively stationary interrupting contact i to establish a loweror second interrupting arc 52 within the lower interrupting chamber 35.Compression springs 53- encircle the lower ends of the operating rods37', being disposed between the conducting bridge 33 and the lowermetallic plate 54 of the lower interrupting chamber 35. Thus, thecompression springs 53 bias the operating rods 31 and both bridgingmembers 88, 39 downwardly toward the circuit opening position.

I have provided a plurality, in this instance four, finger contacts 56(Fig. 5) disposed in recesses 59 provided in the intermediate casting 28and securedthereto. by any suitable means, such as the screws Bil. Thefinger contacts 55 bear against the side wall 51a of a piston 5'!movable within an operating cylinder 6! formed as an integral part ofthe casting 28 (Fig. 5). The walls of the casting 28 also provide aplurality, in this instance four, fluid conducting passages 62 and shownmore clearly in Figs. 3 and 5. The piston 51 is biased downwardly by acompression spring 63 which also serves to provide the requisite contactpressure between the pressure-generating contacts 4?, 48 when in theclosed circuit position of the interrupter, it being noted that therelatively stationary pressure-generating contact 38 is secured to andmovable with the piston 51.

From the foregoing discussion it will be apparent that in the closedcircuit position of the interrupter the electrical circuit therethroughincludes lower line terminal 55, stationary guide casting 19, lowermovable contact 29, conducting bridge 38, lower movable interruptingcontact 50, lower relatively stationary interrupting contact 55,metallic plate 36-, intermediate casting 28, finger contacts 5% (Fig.5), conducting piston 51, relatively stationary pressure-generatingcontact is, movable pressure-generating contact 31, upper movableinterrupting contact 45, upper relatively stationary interruptingcontact 45, top metallic plate 32, contact foot 33, and through theterminal stud 58 disposed interiorly of the high voltage condenserbushing 6.

When it is desired to open the electrical circuit through theinterrupter or when overload conditions exist in the electrical circuitcontrolled by the interrupter, suitable mechanism, not shown, isactuated to cause counterclockwise rotative movement ofthe crank arm 2?.This rotative motion of the crank arm 2? causes movement of theintermediately disposed linkage 22, 2-4 and downward motion of the lowermovable contact 20.

I provide a substantially 16 semi-holding tapered orifice contact 64-(see Fig. 7) which makes contacting engagement with the contact 2%. Thistype of moving contact eliminates fingers and has a shock resistinge-fiect in closing. This contact connection between the contacts 64, it!gives a positive connection in opening because of the angle of the taperconnection which has been so designedas to need a slight tap or knock todisengage. So because of the substantially 16 taper, the bridge 38 movesdownwardly with the movable contact 26 during the opening operation.Thus the angle a in Fig. 7 is 3, and must not be too great. Fig. 6 showsa contact construction in which a is too large and hence the contact 2%will not hold to the contact b i-a. Angle a must be less than the angleof friction of rest (or angle of repose) or tan. a must be less than thecoefficient of friction. of rest (or of static friction). For metals onmetals or varies from 8 to 17.5".

The downward motion of the conducting bridge 38 simultaneously causesdownward motion of the operating rods 31 and downward motion of. the.two movable interrupting contacts id, 50 from their respectiverelatively stationary interrupting contacts 45, 5| to simultaneouslydraw twov interrupting arcs lEi, 52 within the respective interruptingchambers 3:4, 35. Also at. the samev time that the separation. takesplace between the. two pairs of interrupting contacts, there also takesplace separation between. the pressure.- e onta ts. 4 4.8. to draw the.pressuregeneratin are 43 withinthe' pressurePgenerati-ng chamber 36'.Consequently, with the construction which I have employed, there resultsthe simultaneous establishment of an intermediately disposedpressure-generating arc and two interrupting arcs within the twointerrupting chambers 34, 35 disposed at opposite ends of thearcextinguishing unit 8.

The establishment of the pressure-generating are 43 creates pressurewithin the liquid, in this instance, circuit breaker oil, disposedwithin the pressure-generating chamber 36 to force said liquid upwardlythrough the fluid conducting passages 62 and into the upper interruptingchamber 34. Also, the oil is forced downwardly from thepressure-generating chamber 36 through two vertically disposed fluidconducting passages 65 into the lower interrupting chamber 36.

The interrupting chambers 34, 35 are of the type set forth in UnitedStates patent application, filed November 11, 1942, Serial No. 465,244,by Leon R. Ludwig, Winthrop M. Leeds and Benjamin P. Baker, now UnitedStates Patent 2,466,469, issued August 27, 1946, and assigned to theassignee of the instant application. For the purpose of illustrating myinvention it is merely necessary to state that the fluid flowingdownwardly through the fluid conducting passages 65 passes radiallyinwardly through three pairs of inlet passages G6, as more clearly shownin Fig. 4, to contact the interrupting arc 52 and pass through orifices6'! to pass out of the interrupting chamber 35 through oppositelydisposed vent passages 68. Reference may be had to the aforesaid Patent2,406,469 for the constructional details of the several plates formingthe interrupting chambers 34, 35. The interrupting action which takesplace in the upper interrupting chamber 34 is identical to that whichtakes place in the lower interrupting chamber 35, the fluid passingupwardly through the passages 62 and into two vertically extendinpassages 69 which communicate with a plurality of pairs of inletpassages 66. Again the fluid after contacting the interrupting are 46passes through orifices 61 and out of the interrupting chamber 34through oppositely disposed vent passages 68 (Fig. 4).

During the interruption of high powers, the pressure generated at thepressure-generating arc 49 will be sufficient to hold the piston 51upwardly in its charged position against the downward bias exerted bythe compression sprin 63. However, during the interruption of lowpowers, where the pressure generated at the pressuregenerating are 49may be insufficient to establish the requisite fluid flow, then the biasof the compression spring 63 will be suificient to overcome the arcingpressure within the pressure-generating chamber 35 and cause downwardmotion of the piston 51 within the operating cylinder 6! formed by thecastin 28. The downward movement of the piston 51 will force the oilupwardly through the passages 62 into the interrupting chamber 34 anddownwardly through the passages 65 into the interrupting chamber 35.

Consequently, I have provided piston means operable durin low currentinterruption to speed up the extinction process exerted upon the twointerrupting arcs 46, 52.

After the arcs have been extinguished, the plunger 10 formed ofinsulating material and secured to the bridging member 39 moves into thecup-shaped dashpot H to halt the downward motion of the bridges 38, 39and operating rods 31. Thus, I have provided a dashpot operable tocushion the stopping of the movable contact structure near the end ofthe opening stroke. When the plunger HI enters the dashpot H to therebyhalt the downward motion of the bridges 38, 39, the lower movablecontact 20 is forcibly Withdrawn from the slight taper aiforded by thecontact 64. This provides an isolating gap in clear oil outside of thearc-extinguishing unit, in the fully open circuit position of theinterrupter, as shown more clearly in Fig. 2.

During the closing operation, the contact 20 is moved upward byclockwise rotation of crank arm 21 to thereby engage the contact 64. Thecontact 64 is forced upwardly with the contact 20 against the biasexerted by the compression springs 53 to simultaneously cause theclosing of both pairs of interrupting contacts and the pair ofpressure-generating contacts. Also, the raising of the movablepressure-generating contact 41 causes upward chargin movement of thepiston 51 to force the latter to its upper raised position.

From the foregoing description, it will be apparent that I have providedan improved arcextinguishing unit of the type establishing twointerrupting arcs and a pressure-generating are simultaneously. Thesimultaneous operation results in high speed interruption. Also, theconstruction is positive because of the provision of the 16 taper of thecontact 64. By such a contact construction, the operating rods 31 areforcibly moved downwardly in a simplified manner and there resultsimmediately positive formation of the pressure-generating arc and thetwo interrupting arcs. The interrupting chambers are operable to causeeffective fluid flow toward the interrupting arcs to consequently brinabout their interruption, and the piston 51 assures speedy interruptionof the low powers.

The compression spring 63 not only biases the piston 51 to its downwardopen position but also provides the requisite contact pressure betweenthe pressure-generating contacts 48, 41. The dashpot H cushions thestopping of the movable contact structure and permits the lower movablecontact 20 to be forcibly withdrawn from the unit 8 to provide theisolating gap in the open circuit position of the interrupter.

It will be noted that the constructional features of my improved type ofinterrupter are exceedingly simple and positive in operation. Thprovision of the pressure-generating are at the central portion of theunit 8 permits upward and downward fluid flow toward the interruptingchambers disposed at the ends of the arc-extinguishing unit 8. Also, theupward and downward forces tend to balance or neutralize the stressesimposed upon the unit 8.

Although I have shown and described a specific structure, it is to beclearly understood that the same was merely for the purpose ofillustration and that changes and modifications may readily be madetherein by those skilled in the art without departing from the spiritand scope of the appended claims.

I claim as my invention:

1. In a circuit interrupter, an operating cylinder, a piston operablewithin the cylinder, a contact secured to and movable with the piston,an other contact cooperable with the said contact to establish an arc,an aperture provided in the piston, and contact means including acontact rod carrying the said other contact movable through the apertureto move the piston in sliding relationship to its charged position.

2. In a circuit interrupter, an arc-extinguishing unit, means defining apair of vented interrupting chambers disposed at opposite ends of theunit, means defining a pressure-generating chamber disposed intermediatethe ends of the unit, a pair of interrupting contacts separable in eachinterrupting chamber, a pair of pressure generating contacts positionedwithin the pressure-generating chamber, piston means disposed within thepressure-generating chamber and including a piston operable within anoperating cylinder, and rod means extending through the piston andopcrating cylinder in sliding relationship for simultaneously causingthe separation of the three pairs of contacts and also closing chargingmovement of the piston.

3. In a circuit interrupter, movable contact structure, a movablecontact carriage having a limited degree of motion for causing theactuation of the movable contact structure, means defining an orificecontact carried by the carriage, and a rod-shaped movable contactengageable with the orifice contact to cause actuation of the carriage.

4. In a circuit interrupter, a movable contact carriage having a limiteddegree of motion, an orifice contact carried by the carriage, a rodshaped movable contact engageable with the orifice contact to causeactuation of the carriage, and the angle of taper being substantially16.

5. In a circuit interrupter oi" the liquid break type, an elongatedarc-extinguishing unit, a vented interrupting chamber disposed at oneend of the unit, a pressure-generating chamber disposed intermediate theends of the unit, a piston chamber positioned adjacent thepressure-generating chamber, a piston movable within the piston chamber,a second vented interrupting chamber disposed adjacent the other end ofthe unit, a pair of separable contacts disposed in each interruptingchamber and also Within the pressuregenerating chamber, and movablecarriage means extending through the piston chamber in slidingrelationship thereto for simultaneously causing the separation of thethree pairs of contacts and charging of the piston.

6. In a circuit interrupter of the liquid treat type, an elongatedarc-extinguishing unit, a vent ed interrupting chamber disposed at oneend of the unit, a pressure-generating chamber disposed intermediate theends of the unit, a piston chamber positioned adjacent thepressure-generating chamber, a piston movable within the piston chamber,a second vented interrupting chamber disposed adjacent the other end ofthe unit, a pair of parallel extending operating rods, a rodshapedmovable contact extending through the piston chamber and secured to theoperating rods to cause charging of the piston, a relatively stationarycontact cooperable with the rod-shaped contact to establish aninterrupting arc in the vented interrupting chamber, a movablepressuregenerating contact secured to the rod=shaped contact andcooperable with a relatively stationary pressure-generating contact toestablish a pressure-generating are within the pressure-generatingchamber, and a second rod-shaped movable contact secured to theoperating rods and cooperable with a relatively stationary contact toestablish a second interrupting are within the other interruptingchamber.

7. In a circuit interrupter of the liquid break type, anelongatedarc-extinguishing unit, a vented interrupting chamber disposed at oneend of the unit, a pressure-generating chamber disposed intermediate theends of V the unit, a piston chamber positioned adjacent the pressuregenerating chamber, a second ventedinterru'pt; ing chamber disposedadjacent the other end of the unit, a pair of parallel extendingoperating rods, a rod-shaped movable contact extending through thepiston chamber and secured to the operating rods, a relativelystationary contact co-' operable with the rod-shaped contact toestablish an. interrupting are within the vented interrupting chamber, amovable pressure-generatingcontact secured to the rod-shaped contact andcooperable with a relatively stationary pressuregenerating contact toestablish a pressure gencrating are within the pressure-generatingchamber; a second rod-shaped movable contact secured to the operatingrods and cooperable with a relatively stationary contact to establish asecond interrupting are within the other interrupting chamber, a pistonoperable Within the piston chamber, and the relatively stationarypressuregenerating contact being secured to and movable with the piston.I

8. In a circuit interrupter of the liquid break type, an elongatedarc-extinguishing unit, a vented interrupting chamber disposed at oneend of the unit, a pressure-generating chamber disposed intermediate theends of the unit, a piston chamber positioned adjacent thepressure-generating chamber, a piston movable within the piston chamber,a second vented interrupting chamber disposed adjacent the other end ofthe unit, movable carriage means including a pair of parallel extendingoperating rods, a roashapd movable contact extendin through thepistonchamber in sliding. relation with respect to the piston to causethe charging thereof and secured to the operating rods, a relativelystationary contact co operable with the rod-shaped contact to establishan interruptin are within the vented interruptmg chamber, a movablepressure-generating contact secured to the rod-shaped contact and cooperable with a relatively stationary pressuregenerating" Contact toestablish a pressure-generating are within the pressure-generatingchamber, a second rod-shaped movable contact secured to the operatingrods and cooperable' with a second relatively stationary contact toestablish a second interrupting are within the other internsrnann'cnscirca The following references are of record in the file of this patent:

UN ITED STATES PATENTS Numbe Name Date 2,160,673 Prince May 30, 19392,238,027 Prince Apr. 8, 1941 2,372,589 Leeds et a1 Mar. 27, 19452,337,589 Kessel'ring et al Oct. 23, 1945 2,406,469 Ludwig et al Aug.27, 1946

